package liangtWorkSpace.rsa;

import org.apache.commons.codec.binary.Base64;
import sun.misc.BASE64Decoder;

import javax.crypto.Cipher;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

public class RSAEncrypt {
	private static Map<Integer, String> keyMap = new HashMap<Integer, String>();  //用于封装随机产生的公钥与私钥
	public static void main(String[] args) throws Exception {
		//生成公钥和私钥
		genKeyPair();
		//加密字符串
//		String message = "df723820";
		String message = "MIIBVgIBADANBgkqhkiG9w0BAQEFAASCAUAwggE8AgEAAkEAw/yr77ppzSPi+CEk2ZyKcbs6nA5M7QnSTAqis2NEsg4BP3vgwpa6aL1Oq7162484+2QKlu8fkQRex+CdOpO2nQIDAQABAkEAp2j0wWD9sTJ/VS6SmKPECqRAyz7X7P6fuT64ff1El8Yopvvd2gly1hm+oAsxT9NmQmDvVD32NwsfQLLOs0Z77QIhAPQ3oaP+poIELaaSlVgDeoRuy+TOXORe1j8u+wR5M7HrAiEAzXFW8XsZOzm931dBDXqg96LFu34uZE/Iut55d327D5cCIC9Lps4vvudnD8A2mx2UbuG+41XIcUz44N0TqCFRp6VJAiEAwWbxcmNwXVD+bkK1+vp2jqmte9RN2CFD1qeZseOrNgECIQDZPVcLR8WAlYhupinCiYYyIRSUG79en9ouj9sX32KKbA==";
		System.out.println("随机生成的公钥为:" + keyMap.get(0));
		System.out.println("随机生成的私钥为:" + keyMap.get(1));
//		String messageEn = encrypt(message,keyMap.get(0));
		String messageEn = rsaEncrypt(message,keyMap.get(0));
		System.out.println(message + "\t加密后的字符串为:" + messageEn);
		String messageDe = decrypt(messageEn,keyMap.get(1));
		System.out.println("还原后的字符串为:" + messageDe);
	}

	/** 
	 * 随机生成密钥对 
	 * @throws NoSuchAlgorithmException 
	 */  
	public static void genKeyPair() throws NoSuchAlgorithmException {  
		// KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象  
		KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");  
		// 初始化密钥对生成器，密钥大小为96-1024位  
		keyPairGen.initialize(512,new SecureRandom());
		// 生成一个密钥对，保存在keyPair中  
		KeyPair keyPair = keyPairGen.generateKeyPair();  
		RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   // 得到私钥  
		RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  // 得到公钥  
		String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
		// 得到私钥字符串  
		String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));  
		// 将公钥和私钥保存到Map
		keyMap.put(0,publicKeyString);  //0表示公钥
		keyMap.put(1,privateKeyString);  //1表示私钥
	}  
	/** 
	 * RSA公钥加密 
	 *  
	 * @param str 
	 *            加密字符串
	 * @param publicKey 
	 *            公钥 
	 * @return 密文 
	 * @throws Exception 
	 *             加密过程中的异常信息 
	 */  
	public static String encrypt( String str, String publicKey ) throws Exception{
		//base64编码的公钥
//		byte[] decoded = Base64.decodeBase64(publicKey);
		byte[] decoded = Base64Util.decoder(publicKey);
		RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
		//RSA加密
		Cipher cipher = Cipher.getInstance("RSA");
		cipher.init(Cipher.ENCRYPT_MODE, pubKey);
//		String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
		String outStr = Base64Util.encoder(cipher.doFinal(str.getBytes("UTF-8")));
		return outStr;
	}

	/** 
	 * RSA私钥解密
	 *  
	 * @param str 
	 *            加密字符串
	 * @param privateKey 
	 *            私钥 
	 * @return 铭文
	 * @throws Exception 
	 *             解密过程中的异常信息 
	 */  
	public static String decrypt(String str, String privateKey) throws Exception{
		//64位解码加密后的字符串
//		byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
		byte[] inputByte = Base64Util.decoder(str);
		//base64编码的私钥
//		byte[] decoded = Base64.decodeBase64(privateKey);
		byte[] decoded = Base64Util.decoder(privateKey);
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
		//RSA解密
		Cipher cipher = Cipher.getInstance("RSA");
		cipher.init(Cipher.DECRYPT_MODE, priKey);
		String outStr = new String(cipher.doFinal(inputByte));
		return outStr;
	}
	//base64 解码
	public static String decode(byte[] bytes) {
		return new String(Base64.decodeBase64(bytes));
	}

	//base64 编码
	public static String encode(byte[] bytes) {
		return new String(Base64.encodeBase64(bytes));
	}



	public static String rsaEncrypt(String input, String rsaPublicKey) {
		String result = "";
		try {
			// 将Base64编码后的公钥转换成PublicKey对象
			byte[] buffer = Base64Util.decoder(rsaPublicKey);
			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
			X509EncodedKeySpec keySpec = new X509EncodedKeySpec(buffer);
			PublicKey publicKey = keyFactory.generatePublic(keySpec);
			// 加密
			Cipher cipher = Cipher.getInstance("RSA");
			cipher.init(Cipher.ENCRYPT_MODE, publicKey);
			byte[] inputArray = input.getBytes();
			int inputLength = inputArray.length;
			System.out.println("加密字节数：" + inputLength);
			// 最大加密字节数，超出最大字节数需要分组加密
			int MAX_ENCRYPT_BLOCK = 117;
			// 标识
			int offSet = 0;
			byte[] resultBytes = {};
			byte[] cache = {};
			while (inputLength - offSet > 0) {
				if (inputLength - offSet > MAX_ENCRYPT_BLOCK) {
					cache = cipher.doFinal(inputArray, offSet, MAX_ENCRYPT_BLOCK);
					offSet += MAX_ENCRYPT_BLOCK;
				} else {
					cache = cipher.doFinal(inputArray, offSet, inputLength - offSet);
					offSet = inputLength;
				}
				System.out.println("加密内容：");
				System.out.println("内容结果："+resultBytes);
				resultBytes = Arrays.copyOf(resultBytes, resultBytes.length + cache.length);
				System.arraycopy(cache, 0, resultBytes, resultBytes.length - cache.length, cache.length);
			}
			result = Base64Util.encoder(resultBytes);
		} catch (Exception e) {
			System.out.println("rsaEncrypt error:" + e.getMessage());
		}
		System.out.println("加密的结果：" + result);
		return result;
	}
}
